Thinking Binary

Boolean Logic is the bedrock of the digital revolution. Developed by George Boole in the mid-19th century, it is based on a simple set of values: 0 (“FALSE”) or 1 (“TRUE”). In computers, all information is represented by strings of 0s and 1s - multiple representations of binary digits or “Bits”. Bits are physically implemented by two-state devices named transistors. The assembling of transistors forms logic gates - which enables digital circuits to exhibit incredibly complex behaviours in the everyday objects that surround us.

A Biological Computer

Creating customizable logic gates in living cells holds the promise of revolutionizing our ability to dictate the behaviour of organism and the way they react to distinct molecular cues. This involves designing logic circuits capable of linking the many genetic regulatory networks responsible for biologic operations. An ideal genetic logic device should therefore be modular and reusable, enabling scientists to implement any complex logic functions in multiple biological systems. Our goal this summer is to achieve this by using gRNA-dCas9 combinations as the biological equivalent of the wires that connect the different components of electric circuits.
Cas9 (CRISPR associated protein 9) is an RNA-guided DNA endonuclease enzyme that can target and cleave any DNA sequence complementary to its guide RNA (gRNA). Our logic gates will be based upon a derivative of this technology, the catalytically “dead” Cas9 (dCas9) that lacks the ability to cleave DNA. dCas9’s has the very interesting property of acting as programmable transcription regulator. It it can act either as repressor by preventing the binding of the RNA polymerase (RNAP) to the targeted DNA or as an activator when fused to a polymerase recruiting element (the omega subunit of RNAP in E. Coli and VP64 in Yeast).

Third Procedure

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Fourth Procedure

1. Pellentesque ligula lectus, molestie quis magna lobortis.

   1. Praesent sit amet cursus urna. In nec lobortis tellus.
   2. Donec congue, urna non semper interdum.
   3. Que nisi bibendum tellus, sed tempus tellus neque et leo.
   4. Cras laoreet mi sed nulla lobortis, epharetra eros laoreet.

2. Donec convallis elementum convallis. Duis ac purus sem.

   1. Fusce id nunc tellus.
   2. Maecenas vitae ornare arcu.
   3. Phasellus gravida congue turpis, eu bibendum lorem molestie eget.
   4. Phasellus tristique sapien non placerat eleifend.